AIRWAY MANAGEMENT IN NEUROSURGERY 1 The Philippine General Hospital (PGH) 2 University of the Philippines (UP) 3 UP-PGH 4 DIFFICULT AIRWAY MANAGEMENT IN NEUROSURGERY GERALDINE RAPHAELA B. JOSE MD FPBA CLINICAL ASSOCIATE PROFESSOR DEPARTMENT OF ANESTHESIOLOGY UNIVERSITY OF THE PHILIPPINES PHILIPPINE GENERAL HOSPITAL 4TH ASIAN SOCIETY FOR NEUROANESTHESIA AND CRITICAL CARE (ASNACC)/ 22ND ANNUAL MEETING OF THE KOREAN SOCIETY FOR NEUROSCIENCE IN ANESTHESIOLOGY AND CRITICAL CARE BUSAN, KOREA APRIL 4, 2015 5 Lecture Objectives • To review airway issues that might be encountered in the neurosurgical patient 1) Intracranial Dynamics and the airway 2) The “Anticipated Difficult Airway” clinical scenarios in Neuroanesthesia and their respective management options 3) The potential “Postoperative Airway- Related Risks” due to the Neurosurgical procedure 6 DISCLAIMER: This author has made every effort to ensure that the patient care recommended herein is in accord with current accepted standards and practice. In view of the changing nature of medical knowledge, this author warrants that the information and views contained herein may be controversial or with personal bias in the context of his own clinical practice experiences; thus, the lecturer disclaim all responsibility for any errors or omissions or for the results obtained from use of the information contained herein. Furthermore, the lecturer is neither sponsored/commissioned by nor in a commercial relationship with equipment manufacturers of equipment cited herein. 7 Neurosurgical Patient Airway Demographics PATIENT PROFILE 8 1) Patients expected/anticipated to have Difficult Airways: a) Acute cervical spine injury/instability with immobilization b) The patient’s head may be fixed in a Halo/Stereotactic head frame. c) Conditions with high incidence of difficult airway management or failed intubation i. The patient for pituitary surgery ii. Patients with Chronic Spine Disease with Myelopathy iii. Patients S/P occipito-cervical or cervical fusion iv. Patients S/P temporal neurosurgical procedures 9 1) Patients expected/anticipated to have Difficult Airways: d) Patients presenting for Functional Neurosurgery (“awake” cranial or spine procedures) or embolization procedures d) Pediatric patients with Cranio-maxillo- facial dysmorphic syndromes, Cranio- spinal Dysraphisms, Congenital Hydrocephalus with Macrocephaly 10 2) The “UNPREPAREDNESS” in a failed airway or Unanticipated Difficult Airway situation becomes an even greater challenge in: a. Patients at risk for cerebral aneurysm rupture b. Patients at risk of herniation c. Head-injured patients d. Patients with “missed/undetected” myelopathy secondary to an underlying chronic cervical spine disease 11 3) Other challenges & considerations: a. the patient in the unusual positions during surgery (e.g., prone, sphinx, military, sit-up) b. extubation after a prolonged surgery c. Peculiar sensitivity of some patients with central nervous system (CNS) disease to the effects of hypnotic agents 12 Intracranial Dynamics and the Airway PATIENT PROFILE 13 Unique challenges 1. Airway management in the face of intracranial hypertension or limited intracranial compliance 2. During the processes of achieving, maintaining, and/or rescuing the difficult neurosurgical airway, there is the need to: a) balance and maintain CNS hemodynamics (CBF, CBV, CMRO2, CSF dynamics), b) avoid increases in ICP, yet c) maintain cerebral/spinal perfusion Bekker AY, Mistry A, Ritter AA, et al: Computer simulation of intracranial pressure changes during induction of anesthesia: comparison of thiopental, propofol, and etomidate. J Neurosurg Anesthesiol 11:69–80, 1999. 14 • FACTS: • Airway obstruction and difficult Bag/Mask Ventilation may quickly lead to hypercarbia, hypoxemia, and increased CBF aggravating intracranial hypertension • Laryngoscopy and intubation result in acute increases in ICP and MAP (also undue cranio-cervical spine motion) • THE PRIMARY GOALS are to avoid: • further increases in ICP and • further neurologic injury. Burney RG, Winn R: Increased cerebrospinal fluid pressure during laryngoscopy and intubation for induction of anesthesia. Anesth Analg 54:687–690, 1975. 15 General Airway Considerations in Patients for Craniotomy Is there an “ideal” technique? CLINICAL STRATEGIES 16 1) Airway Assessment (history and PE) of the neurosurgical patient requires similar considerations a) A previous history of difficult airway management (mask ventilation, laryngoscopy, and/or intubation) warrants particular attention 17 b) Patients with signs and symptoms of Intracranial vascular insufficiency should receive special attention to neck position not only during tracheal intubation & surgery but also in the perioperative period. i. “Beauty parlor stroke syndrome” & “Adolescent stretch syncope” [vertebro-basilar insufficiency], ii. Transient ischemic attacks (TIA), iii. Stroke, and iv. Presence of carotid bruit • Weintraub, et. al. (MRA flow analysis of 160 cases in 1998): “sustained neck hyperextension greater than 12 minutes appears to be a neglected potential hemodynamic factor that may play a pivotal role in the pathogenesis of perioperative stroke” Stroke. 1998;29:1644-1649 18 MOUTHS Acronym (modified from Davis J, 1991) Components Description Assessment Activities Measure hyomental Length, subluxation distance (A) Mandible and anterior displacement A of mandible Assess and measure mouth opening in Base, symmetry, Opening range centimeters or patient’s own 3-finger breadth. 0 Assess pharyngeal Visibility (to include structures and classify Uvula palatal configuration) [Mallampati Class] Teeth Dentition Assess for presence of loose teeth and dental appliances, occlusion (bite), incisor prominence Flexion, extension, Assess all ranges of movement Head rotation of head/neck [Belhouse-Doré Grade, axial rotation, and cervical spine instability, sternomental distance] Upper body AP Identify potential impact on airway control abnormalities by large breasts, buffalo hump, kyphosis, Silhouette (to include thyroid short (position of larynx to base of the cartilage tilt) tongue) & large neck circumference, etc. 19 HOWEVER, the limitations of difficult airway prediction via “bedside” screening tests are increasingly being recognized within anesthesia. “ …we believe that attempts at prediction are much less important than knowing what to do when difficulty is encountered…the clinical value of these bedside screening tests for predicting difficult intubation remains limited.” 20 Summary of Pooled Sensitivity and Specificity of Commonly Used Methods of Airway Evaluation EXAMINATION SENSITIVITY (%) SPECIFICITY (%) Mallampati classification 49 86 Thyromental distance 20 94 Sternomental distance 62 82 Mouth opening 46 89 Anterior tilt of larynx* 70 95 Data derived from Shiga T, Wajima Z, Inoue T et al: Predicting Difficult Intubation in Apparently Normal Patients: A Meta-analysis of Bedside Screening Test Performance. Anesthesiology 2005; 103: 429 * Roberts JT, Ali HH, Shorten GD. Using the bubble inclinometer to measure laryngeal tilt and predict difficulty of laryngoscopy. J Clin Anesth 1993;5:306–309 Shiga, et al. META-ANALYSIS: “…only poor to moderate sensitivity and moderate to fair specificity” 21 • In clinical practice, unexpected difficulties may occur in 25-30% of cases. Approximately 50% of these had been labelled as “pseudo-difficulties” resulting from: 1) unskilled operators, 2) incorrect execution of maneuvers, or 3) lack of working guidelines/protocols SIAARTI-DASG, 2005 22 2) In addition to the history and physical examination, preoperative • plain radiographs, • computed tomography (CT) or • magnetic resonance imaging (MRI), & • angiography may give valuable information of the patient’s intracranial status - signs of increased ICP presence of hemorrhage/infarct/vasospasm/edema Bedford RF, Morris L, Jane JA: Intracranial hypertension during surgery for supratentorial tumor: correlation with preoperative tomography scans. Anesth Analg 61:430–433, 1982 23 “Copper beaten” skull • Signs of increased intracranial pressure on a skull plain x-ray – Increased vascular markings – Widening of the sella turcica – Erosion of the sella turcica – Gyri may make prominent markings on the inner table of the skull – The pineal gland is displaced from the midline. Tuite GF, Evanson J, Chong WK et-al. The beaten copper cranium: a correlation between intracranial pressure, cranial radiographs, and computed tomographic scans in children with craniosynostosis. Neurosurgery. 1996;39 (4): 691-9 24 T1 post-gadolinium 3-D DTI Fluid Attenuated Proton Density Gradient Echo Diffusion Tensor Imaging Inversion Recovery 25 CT appearance of normal brain. CT scan appearance of tumor with edema and midline shift. Lesions associated with greater than 10 mm in midline shift or cerebral edema usually indicate intracranial hypertension Bedford RF, Morris L, Jane JA: Intracranial hypertension during surgery for supratentorial tumor: correlation with preoperative tomography scans. Anesth Analg 61:430–433, 1982 26 CT scan appearance of Intracranial Hemorrhage Acute Sub-acute Chronic 27 Branch of the Left PCA Basilar Right Vertebral artery artery VASOSPASM (CEREBRAL ANGIOGRAM) 28 3) For “Difficult Airway suspects” (2ry to extensive skull-base pathologies) due for elective cranio-facial procedures: PEAE 1 and airway UTZ 2 as adjunctive assessment tools may be valuable in the airway approach decision-making 1 Rosenblatt W, Ianus AI, Sukhupragarn W, Fickenscher A, Sasaki C. Preoperative endoscopic airway